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by Alex Zadnik and Chris Hesman
Did you know Yes Energy (formerly TESLA Forecasting) provides forecasts in nearly 40 countries and we’ve been doing this for 30 years?
Today we take a deep dive into Australian markets to explore the effect of high dew point on Australian electricity demand.
Background
The Australian summer of 2023/2024 saw elevated electricity demand due to the combination of high dry-bulb air temperatures (i.e. air temperature) and high dew point temperatures, particularly for Brisbane and Sydney.
The minimum temperature in Brisbane failed to drop below 20 degrees Celsius between January 1 and March 15, due in large part to elevated moisture levels in the atmosphere.
Radiative cooling of the Earth’s surface is less efficient when moisture levels are high (and it’s contact with the Earth’s surface that cools temperatures overnight). Days where the temperature exceeded 30 degrees in Brisbane were often accompanied by high dew point temperatures in the low 20s.
January 22 saw the dew point temperature reach a more extreme 25.7 degrees C, which in combination with a dry bulb value of 34.1 C and light winds, pushed the apparent temperature (which combines air temperature, dew point temperature and wind) close to 40 C.
Later, on February 29, 2024, Sydney’s dew point temperature peaked at 25 C at 2:30 p.m., while the air temperature at the same time was 32.2 C. (The dew point temperature defines the temperature at which air needs to be cooled for water to condensate.) With relatively light winds at this time, the apparent temperature reached 36.6 C. To a human observer not exposed to the wind (in a house or sheltered backyard), it likely felt even hotter. It’s also speculated that evaporative air-conditioning units become less efficient and effective when dew-point temperatures reach the mid-20s, which would motivate users to change settings and draw on more energy.
There were other instances through the summer of high dew points in Sydney, with a value of 27.6 C on January 11, which was a new record for Observatory Hill, a park in central Sydney. Contributing to the record and near-record high dew point temperatures were record sea surface temperatures off the coast of Sydney, particularly on February 29. Warm sea surface temperatures lead to higher rates of evaporation, boosting the dew point temperature for nearby locations.
Sea surface temperatures near Sydney exceeded 26 degrees on February 27. A new temperature record of 26.75 C was measured at the Manly Hydraulics laboratory on March 8, 2024.
Demand Analysis for Notable High Dew Point Days
We summarized two notable high dew point days from the 2023/2024 summer and their electricity demand (one here and one in our case study).
New South Wales February 29, 2024
Operational demand in New South Wales on the 29th was the highest it’s been since February 2020, peaking at 13,643 MW. This demand falls within the top 1% of observed load for the NSW region. The dew point on the 29th reached 25 C compared to 21.5 C for the average comparable days with demand 2.3 GW higher on this day compared to the comparable days.
NSW, Australia Electricity Demand Analysis from February 29, 2024. Actual demand versus Average Comparable Demand (from comparable days in historical record).
The dew point for this day was in the top 1% for Sydney on the 29th while the dry bulb temperature was in the top 5%. Given that Australia’s peak demand flex is primarily driven by air-conditioning demand, temperature and humidity are critical variables to include in a load forecast model.
Taking this a step further, we can use dew point variables to improve load forecast precision. The TESLA model routinely uses the following weather variables: temperature, humidity and/or dewpoint, cloud cover, irradiance, wind speed and direction, and precipitation.
Want to see the full analysis and the results of our case study? See the MetraWeather/Yes Energy case study.
About the author: Alex Zadnik has more than twenty years’ experience in the provision of meteorological services and solutions to a wide range of industries, including the energy sector. He holds a Bachelor of Science from the University of Melbourne and dual Master of Business Administration/Master of Analytics Management from Melbourne Business School.
About the author: Since 2018, Chris Hesman has specialized in building and maintaining gas and power demand forecasts in Europe and the APAC region. At Yes Energy, Chris is a forecast analysis manager based in Auckland and oversees all power and gas forecasts in the APAC region, ensuring accurate and reliable energy predictions.
